I’ve been trying to tackle this one and I finally did! Check it out:
http://www.tcscblog.com/start-the-organization-browser-at-any-account-name/
Excerpt:
I’m a huge fan of the SharePoint 2010 Organization Browser, the Silverlight web part that displays the company hierarchy based off of the Active Directory Manager field. However, my biggest complaint was that there was no way to set the default user – meaning I want when the page loads for the focused user to be say a CEO or Department Head instead of me. The easiest solution would be to promote me to CEO, but that didn’t fly to well in the office. So, I had to turn elsewhere.
SharePoint Adam 
10/04/2013 at 5:38 am
What a pity… I had found this blog post before, but now I see that the page http://www.tcscblog.com/2011/07/29/start-the-organization-browser-at-any-account-name/ does not exist any more.
02/05/2015 at 2:15 pm
Fixed!
10/16/2014 at 5:07 pm
The link above to how you did this doesn’t work. 😦
02/05/2015 at 2:11 pm
Fixed! Sorry about that.